Actuation mine simulator

ABSTRACT

An actuation mine simulator system which enables realistic training  experce in mine sweeping operations without the danger accompanying use of live mines. The actuation mine simulator is preprogrammed to respond at predetermined time intervals to actuation by large objects such as ships. The mine simulator includes buoyant flares for signaling actuation, a tethered float having a signal beacon for facilitating recovery, and an underwater acoustic transmitter for locating the simulator at the conclusion of training exercises.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention pertains to sea mine training devices, and moreparticularly to such devices which respond to the proximate presence ofa large object by releasing a visible signal.

2. Description of the Prior Art

Prior mine simulators have utilized a number of service mine componentsso as to duplicate service mine response to a given target object. Suchmine simulators are bulky, including large casings which must beweighted with inert material for negative buoyancy. Since thesesimulators are often planted from aircraft or from the sides of ships asare real mines, the final mine placement on the sea floor is not exact.

U.S. Pat. No. 3,709,148 issued to Costley et al. discloses a drill minewhich has the same operational and physical characteristics as a servicemine. The Costley et al. mine is provided with apparatus for indicatingmine actuation, and for facilitating retrieval thereof. U.S. Pat. No.2,949,853 issued to C. C. Vogt discloses another prior mine simulatorwhich releases a tethered float which includes a smoke signal toindicate actuation of the mine simulator. U.S. Pat. No. 3,086,464 issuedto F. E. Butler et al. discloses a detachable practice mine section,which, upon activation releases a float, after a predetermined delay,which in turn activates a visible signal indicating actuation of themine simulator and also the location thereof. U.S. Pat. No. 2,912,929issued to R. D. Mattingly et al. discloses a submarine drill mineparticularly suited for planting in shallow water. When actuated, asurface signal is produced, comprising a charge of chemical which uponreaction with water, forms a gas which in turn spontaneously igniteswhen exposed to oxygen in the atmosphere at the surface of the water toform a bright flame and large volume of smoke. Each of these U.S.Patents should be studied to gain an appreciation for the scope of theprior art.

SUMMARY OF THE INVENTION

The problems and inconveniences inherent in prior mine simulators havebeen overcome by the present actuation mine simulator which includes aspecially designed water tight housing enclosing instrumentation and atethered float containing a plurality of separate flare signals. Theflares may be launched according to a predetermined sequence to indicatemine actuation. A permanent record is maintained of all ship actuationsand may be utilized in post exercise analysis. The mine simulator of thepresent invention also includes a specially designed search coil, andacoustic transmitter for facilitating location of the simulator afterthe conclusion of mine exercises, and a beacon attached to a tetheredfloat for facilitating night time simulator location and recovery.

BRIEF DESCRIPTION OF THE DRAWING

Further advantages of the present invention will emerge from adescription which follows of the preferred embodiment of an actuationmine simulator according to the invention, given with reference to theaccompanying drawing figures, in which:

FIG. 1 illustrates the operational environment of the actuation minesimulator, including planting, on station, and recovery phases;

FIG. 2 illustrates a side view partially broken out of an actuation minesimulator according to the invention;

FIG. 3 illustrates an end view of the mine simulator case having thealuminum nose piece removed;

FIG. 4 illustrates an end view of an actuation mine simulator case tailplate shroud with the float assembly removed;

FIG. 5 illustrates a perspective view of the interior of an actuationmine simulator case;

FIG. 6 illustrates a side view of a float assembly;

FIG. 7 illustrates the functional relationship between the actuationmine simulator components; and

FIG. 8 illustrates a sectional view of a float assembly.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The actuation mine simulator of the present invention is used in theactuation mine simulator system, and other inventions related thereto,filed with the present invention, include the planting and storage rackand release mechanism, Ser. No. 877,545 filed Feb. 13, 1978, the flarerelease system, Ser. No. 877,547 filed Feb. 13,1978, and the underwatersearch coil, Ser. No. 877,546 filed Feb. 13, 1978. Also, U.S. Pat. No.3,960,087 issued to Beatty et al. teaches a flare which may be usedwithin the actuation mine simulator system.

Referring now to the drawings and in particular to FIG. 1, there isshown the operational environment of the actuation mine simulatorsystem. Mine tender 10 having crane 11 is shown supporting minesimulator planting rack 310 above a precise point on the sea floor whereplacement of a mine simulator is desired. Helicopter 12 is similarlyshown transporting a battery of simulator planting racks 311 to a remotelocation for simulator placement. Simulator 110 is shown moments afterrelease from planting rack 310, and tethered float 210 is shownbeginning to separate from simulator 110. Round aluminum nose piece 112is shown striking the sea floor while float 210 is closely tethered byline 211. Close proximate approach by target ship 13 causes actuation ofsimulator 110 and release of buoyant flare 242. Flare 241, previouslyreleased, has ignited upon approach to the surface and displays a smokesignal.

During the recovery phase, line 211 has been severed permitting floatassembly 210 to reach the surface, trailing the recovery line 212.Beacon 261 has been actuated by approach to the surface and conditionsof darkness. During float release, instrumentation cable 111 has pulledfree of float 210. At the conclusion of mine exercises, mine tender 10returns and retrieves mine simulator 110 by means of recovery line 212attached to float assembly 210. The recovered mine 110 is returned tothe simulator planting rack 310 for storage and transport to a mine shopfor maintenance.

Referring now to FIG. 2 there is shown mine simulator 110 in itsassembled configuration. Basic subassemblies of mine simulator 110include mine case 110A which is water tight to provide housing forinstrumentation in instrumentation rack 117, round aluminum nose piece112 having apertures 113 formed therein, tail plate shroud assembly 118and float assembly 210. Aluminum nose 112 is attached to mine case 110Aby a rod and nut assembly 125A. Aluminum nose 112 insures properorientation upon contact with sea floor, and serves as a sacrificialcathode for cathodic protection of stainless steel mine simulator 110exposed to electrolysis in sea water.

Mine case 110A has a plurality of fins 114 attached thereto. Fins 114,preferably 4 in number, serve to orient mine simulator 110 withinplanting rack 310, help mine simulator 110 scour into a sandy sea floorto help anchor the simulator, and provide means for attachment ofrecovery lines or planting rack safety pins. Fins 114 have auxiliaryhandling slots 115 and safety pin holes 116.

Tail plate shroud assembly 118 is attached to mine case 110A bycircumferential attachment cinching member 119 in a conventional manner.Tail plate shroud assembly 118 serves to house coiled recovery line 212which may be seen through apertures 123. Apertures 123 serve to releasetrapped air to prevent excess buoyancy of simulator 110, the same as doapertures 113 in aluminum nose piece 112. Recovery line 212 passesthrough a relieved notch 124 in gasekt 154 and attaches to a recoveryharness 121 at attach points 122.

Float assembly 210 shown retained to tail plate shroud assembly 118,includes beacon 261, which has a specially designed power circuit toprevent magnetic interference with simulator instrumentation, flarechamber caps 214, and handling line 213.

Referring now to FIG. 3 there is shown acoustic transmitter 131 whichprotrudes a short distance underneath round aluminum nose piece 112.Acoustic transmitter 131 broadcasts a distinctive signal to aid in thelocation of the mine case after completion of mine exercises. Thedistinctive signal is audible to either shipboard sonar or diver handheld sonar.

Referring now to FIG. 4 the tail plate shroud assembly is shownincluding gasket 154, hydrophone 162, hydrostatic switch 161, pressuredetector 165, vent plug 164, depth compensator 163, friction retardedreel 151, squib actuated guillotine line cutter 152, and central lineguide 153. The functional interrelation of the various components ofactuation mine simulator 110 will be explained below.

FIG. 5 illustrates in perspective the interior of mine case 110A.Acoustic transmitter 131 and search coil 133 are shown in the installedposition. Acoustic transmitter 131 extends through the end of mine case110A as illustrated in FIG. 3. Also in FIG. 5 is shown O-ring sea 135which seals against tail plate shroud assembly 118 to provide watertight integrity to the interior of mine case 110A.

Referring now to FIG. 6 there is shown a buoyant flare launchingplatform or housing 210. Housing 210 has a plurality of flare cavitieswhich are sealed from communication with the ambient by detachable cap214 which has O-ring seal 214A and covering flange 214B. Detachable cap214 is secured in place by means of a plurality of shear pins 214Chaving the heads directed toward the center of cap 214, and beingretained in place by safety wire 214D strung around the outside of flarecavity liner 241'. Shear pins 214C are sized and selected to shear uponapplication of force from compressed gas in cylinder 225 which may becarbon dioxide, as will be explained below.

Ejection piston 233, which is sealed against flare cavity liner wall241A by O-rings 236, is slidable almost the entire length of liner 241',and is retained within liner 241' by shoulder 241B during a flareejection. Thus, it may be seen that as compressed gas from cylinder 225passes through aft bulkhead 229, it pressurizes that portion of theflare cavity which is designated 233A in FIG. 8. Pressure in zone 233Acauses ejection piston 233 to apply force to flare 241, which transmitsforce against detachable cap 214, and in doing so causes failure ofshear pins 214C, detaching cap 214 and ejecting flare 241 from itscavity. Since flare 241 is buoyant, after it is ejected from buoyantflare launching platform or housing 210, it rises to the surface.Buoyancy of housing 210, partially lost when piston 233 initially causescap 214 to shear pins 214C and break the seal of O-ring 214A permittingflooding of the flare cavity, is recovered when piston 233 is forcedagainst shoulder 241B near the forward end of cavity liner 241'.

Housing 210 is made buoyant by the inclusion of foam filler 215 or othersuitable buoyant material. Outer skin 216 is joined to suitable cornermembers which may be constructed of aluminum or other common engineeringmaterial as is well known in the art to enclose foam material 215 andthe plurality of flare launching mechanisms.

Stroboscopic beacon 261 is positioned at the forward end of housing 210and is powered by batteries stored in the center of housing 210. Beacon261 is activated by an ambient pressure sensitive switch which enablesbeacon activation only after housing 210 has reached the surface of thewater. Handling line 213 extends around the forward end of housing 210and is intended to facilitate manipulation of housing 210 by scubadivers or other handling personnel.

The aft end of housing 210 includes electronic circuit 240 forsequentially firing the plurality of flares as will be described below.The flare launching mechanism, illustrated and described in Ser. No.877,547 filed Feb. 13, 1978 is retained within flare cavity liner 241'by snap ring 235.

The base or aft end of housing 210 includes coiled line 212 which isconnected between housing 210 and mine case 110A. Line 212 is attachedto housing 210 by a clevis pin at 246'. A second mooring line, notshown, attaches between clevis pin 245' and mine case 110A. Electroniccommunication between the mine case 110A and electronic circuit 240 ismade by an electric cable 111 which attaches a fitting 244' tocommunicate ship count signals to circuit 240.

Referring now to FIG. 7 there is shown schematically the functionalinterrelationships of the various actuation mine simulator componentsthus far described together with firing modules 143, 144 and 145, moduleplug 146, control box 147, ship counter 148, actuation recorder 149,timer 142, and battery pack 141. Capacitor block 154' is showncommunicating with timer 142. Also, signal release selector 240 is showncommunicating with flare release mechanisms for controlling release offlares 241, 242, 243, 244, 245, and 246.

The arrangement of the various components are shown in FIG. 7 by theinclusion within dotted line 110A corresponding to mine case 110A anddotted line 210 corresponding to float assembly 210. Similarly, withindotted line 110A is shown dotted line 117 corresponding to instrumentrack 117 which is retained within water tight mine case 110A. Underwaterinstrument cable 111 is shown communicating with instrument rack 117,attached to mine case 110A and bridging the gap between case 110A andrecovery float 210 to communicate with signal release selector 240.

GENERAL OPERATION

The actuation mine simulator of the present invention is capable ofbeing planted by helicopter or surface craft in waters from 30 to 180feet deep. The submerged time duration of each plant can be preset from1 to 999 hours. Event recorder 149 contained within mine case 110Aprovides an accurate and permanent time account of each ship count forpost-exercise analysis. Up to 99 ship counts can be recorded. Eachsimulator 110 will provide up to 6 firing actuations during a singleplanting. The ship counter 148 returns to its initial setting after eachfiring actuation. The ship counter functions to simulate a minedetonation after a predetermined number of ships or other bodies havebeen sensed. This is in accordance with common mine operationalprocedure.

The simulator is equipped with an underwater acoustic transmitter and afloat locater light beacon which are activated for the recovery phase.The acoustic transmitter or pinger is automatically activated in theevent of case flooding. The mine case 110A is a non-magnetic stainlesssteel case housing the mine sensing and control modules, power supply,acoustic transmitter, and actuation recorder. The mine case weighsapproximately 360 pounds in air and 155 pounds submerged in sea water.Welded to the case are 4 external fins to promote bottom stability andease of mine handling. A nose piece is attached to the forward bulkheadand a tailplate shroud assembly forms the aft end of the mine case allas previously described. In addition to previously described functionsof nose piece 112, it also serves to cushion the shock of water impactwhen the simulator is air dropped from a helicopter. As previouslydescribed it provides cathodic corrosion protection for adjoiningstainless steel mine case 110A and tail plate shroud assembly. Finally,it insures proper bottom orientation for the magnetic search coil bypreventing the mine from settling in a nose down attitude.

The tail plate/shroud assembly is attached to the aft end of the minecase and provides an interface between the mine case and float assembly,a protected mounting surface for the hydrostatic pressure switch 161,pressure detector 165, depth compensator 163, and hydrophone 162,contains the underwater electrical cable 111 which carries power and thefiring signal to the float, and contains the float tether line anchorprovision including a guide 153, a drag device 151 to reduce tether lineshock loads during planting, and a cable cutting device 152 to sever thetether line at recovery time.

Contained within the mine case is an instrument rack assembly consistingof a closed rack or frame 117 in which are located mine componentmodules and the power supply. Some of the instrument rack components arederived from existing service mines. The timer is a low power, solidstate timing device having a self contained clock and switches tocontrol the arming delay and recovery time. The actuation counter 148 isa low power, solid state counting device that allows a predeterminednumber of ship counts to register before completing the firing circuit.The counter also provides a preset intership dead period during which aship count cannot be registered. Actuation recorder 149 is a low power,solid state digital recorder having a self contained clock and tapeprintout. The recorder provides a permanent record of each ship count byevent number and time of occurrence.

The float assembly, FIG. 6, is a cylindrical shaped aluminum shellmeasuring approximately 15 inches high and 18 inches in diameter. In theloaded condition it weighs 100 pounds in air and has a 35 pound buoyancywhen submerged in sea water. The float assembly 210 contains 6 flarecompartments with associated flare release mechanisms, and a solid statefire signal sequencing device 240. Internal cavities of the float arefilled with a closed cell polyurethane foam for additional structuralrigidity and to secure adequate buoyancy in the event of float leakage.When a firing signal pulse is received from the actuation counter 148,the sequencer 240 directs it to the next signal flare to be ejectedaccording to a predetermined sequence.

The flare release mechanism consists of a squib 222, a firing pin orspiked piston 223, an 8 gram CO₂ cartridge or compressed gas cylinder225, and a pneumatically driven flare ejection piston. The cold CO₂ gassystem provides a relatively slow ejection rate with high initial forceto ensure flare release at maximum operating depth. Maximum height of aflare ejection in air is less than 24 inches. After the flare has beenejected, the piston remains seated at the top of a carbon dioxide (CO₂)filled release cylinder, maintaining float buoyancy and protecting thecylinder walls from sea water exposure.

The beacon locator 261 is a self contained, high intensity, flashinglamp. It is activated by reduced hydrostatic pressure as the float risesto the surface during recovery. A light sensor 262 on the beacon turnsthe unit off during daylight to conserve batteries. Operating life ofthe beacon is approximately 100 hours. when used intermittently.

Recovery line 212 is secured to the bottom cover plate of float assembly210 and is a 220 foot reel of 3/8 inch nylon recovery line that remainsattached to the submerged mine case. The recovery line has an ultimatestrength of approximately 3,900 pounds and is used for hoisting thesubmerged mine to the surface and aboard the recovery mine tender 10.The planting rack assembly 310 is an open sided, box frame structure ofaluminum angle designed to enclose and support the mine simulator in avertical nose down attitude while in storage, when being transported,and during planting operations. Rack weight is 125 pounds empty and 580pounds with the mine simulator enclosed. An integral lifting eye andopen base facilitate handling the rack by fork lift or by slingsuspension from an overhead crane. Four racks can be clustered forpalletized handling and storage and for more efficient helicopterplanting operations. The mine simulator is held in position by the finsthat fit into two spaced channel guides located in opposite corners ofthe rack. Spring locking latches prevent the fins from passing throughthe guide. A clevis or safety pin, secured through a channel guide andfin, locks the mine simulator in the rack for handling and storage.During the planting operation the latches are electrically released,allowing the mine simulator to pass through the rack and free fall nosefirst into the water. A release control box and electrical extensioncable allow the mine simulator to be released by an operator in ahelicopter 12 or on board the surface craft 10.

The actuation recorder 149 is a low power, solid state digital recorderthat prints out, in numeric format on tape, a permanent record of eachship count received from the actuation counter 148. The ship count pulseis recorded by event number and the time of occurrence is noted in days,hours, and minutes for post exercise analysis. The event recorderdigital clock is adjusted to current real time during mine assembly. Therecording tape is a 12 foot length of 1/4 inch electro-sensitive papercontained in a small metal cassette. The cassette is removable to allowretrieval of the recorded data and for reloading of fresh tape.

The actuation counter 148 is a low power, solid state actuation counterthat electronically registers a preset number of ship count pulses andthen completes the mine firing circuit after this number of ships havebeen counted. The actuation counter then electronically resets itself tothe initial ship count setting and commences a new series of shipcounts. A dead period is generated after each ship count during whichthe actuation counter is prevented from accepting any additional shipcount pulses for a predetermined period of time.

The timer 142 is a low power, solid state timing device having a crystalcontrol oscillator. The timer has an accuracy of + or - 0.01 percent andcontrols the preset arming delay and recovery time periods. The timeroscillator frequency provides the time base for the actuation recorder149. The timer may be adjusted to set the number of hours before armingwill occur after the device is planted, and the number of hours afterplanting when the recovery phase will begin. Upon completion of the timeto arm after planting, the timer turns on switches applying power to themine sensing and actuation circuits. Upon completion of the plantduration, the timer turns off circuits to remove power and to initiatethe recovery process. During recovery the timer actuates the tether linecable cutter 152 to release the float 210 to the surface, and turns onthe underwater acoustic transmitter 131 to aid in locating the submergedmine simulator.

The underwater search coil 133 is a miniaturized 15 inch long version ofthe five foot service mine search coil. To compensate for the miniaturesize of the search coil, an integral DC amplifier with self containedpower supply is used. The amplifier is equipped with a suppressorcircuit to prevent spurious looks from nearby electronic components inthe instrument rack during the reset function.

The underwater acoustic transmitter is a selfcontained acoustic pingerlocated on the mine case forward bulkhead. The pinger is automaticallyactivated at mine recovery time, or in the event of mine case flooding,to assist recovery personnel in locating the submerged mine simulator. Aself contained timer also allows the pinger to self energize uponcompletion of a 7, 15, 30, or 45 day delay period commencing at mineassembly. Once activated, the operating life of the pinger is in excessof 6 weeks. A light emitting diode mounted on the aft end of the pingerindicates pinger operation.

Capacitor block 154' consists of two electrolitic capacitors wired inparallel and embedded in a foam block. When charged, these capacitorsfurnish the firing energy for igniting the squib within guillotine linecutter 152. Actuation of the squib within line cutter 152 causes linecutter 152 to sever line 211 and release float 210 during the recoveryphase.

The signal release selector 240 is a solid state stepping devicecontaining 6 squib firing circuits. The sequencer processes the shipcount fire signal pulses from the actuation counter 148 to step theselector and trigger, in turn, each squib firing circuit in successiveorder, 1 at a time.

The signal flares 241-246 used in float 210 may be yellow, or green, orother colors and are cylindrical in shape, approximatly 4 inches indiameter by 9.5 inches long and weight approximately 2.67 pounds each inair. They produce a colored smoke for 70 + or - 20 seconds followed by aflame of the same color as the smoke for an additional 25 + or - 10seconds. The flare is armed during ejection from the float and ignitedby exposure of an enclosed sea water battery as the flare approaches thesurface. The flares as previously described may be constructed accordingto the teachings of U.S. Pat. No. 3,960,087.

Loading the signal flares into the flare well ejection cylinders isaccomplished as follows:

Looking down into the flare well cylinder from above the float, insurethat the ejection pistons are bottomed in the cylinder and that thewalls are lined with a thin coating of grease.

Unscrew the flare plastic arming button protective cap, and with thumbinserted in arming button hole, apply lateral pressure to sealing discstem until seal is broken. This relieves any vacuum or pressure that mayexist in the battery cavity, and enables the sealing disc to remainclosed until just before the flare surfaces. This limits flare action tothe surface for maximum visibility.

Insert the flares, base down, into each cylinder. The hole in the flarearming button must seat on the piston alignment boss.

Install O-ring seals on flare well caps, and insert caps in the cylinderon top of the flare. Force lid cap down against arming button springpressure and secure with shear pins. Safety wire the shear pins wherethey extend out of the flare well shoulders.

Unloading unexpended signal flares is accomplished as follows:

Insure that no water is present that could activate an inadvertantlyexposed seawater battery.

Remove safety wire and shear pins.

Remove flare well caps by prying off with finger tips.

Flare may be grasped by fingers, but it may be necessary to tilt thefloat upside down to remove flares. Inspect arming button to make suredetent pins are in locked or safe position.

Replace the plastic arming button protective caps and remove flares topyrotechnic storage area for later use.

Locator beacon 261 is a high intensity, xenon gas discharge, flashingstrobe light mounted in a well on the top center position of therecovery float. The beacon is light weight, non-magnetic and selfcontained. It is powered by a 12 volt battery pack and a solid stateDC/DC inverter. The beacon is activated by reduced hydrostatic pressureas the float rises to the surface during recovery. The beacon willoperate for a minimum of 5 days continuously. A photo electric cell isincorporated in the beacon circuit to extinguish the flashing lightduring daylight hours to conserve battery power.

Flare ejection is powered by a CO₂ cartridge or compressed gas cylinder225 incorporated within a manifold cap assembly attached to float 210 ateach flare cavity. The manifold cap assembly consists of an end cap 229for the bottom of the flare well cylinder to which is attached a gasmanifold system 221 containing CO₂ or other gas cylinder 225 and squibor squib actuator 222. The cap provides a gas tight pressure seal and issecured in place by means of retaining ring 235. Upon receipt of anelectrical firing pulse, squib actuator 222 causes spiked piston orfiring pin 223 to perforate CO₂ or other compressed gas cylinderdiaphragm. The released CO₂ or other gas is directed by the manifoldsystem 221, through passage 228 and the end cap 229 to the bottom of theflare ejection piston 233, forcing it up the flare cylinder and ejectingthe signal flare.

SYSTEM OPERATION

Mine simulator 110 is normally retained in a planting rack forprotection and ease of handling while in storage, when beingtransported, and during planting operations. For long term storage themine simulator is made inert by removing the instruments, sensors,batteries, squib actuators, CO₂ cartridges, and pyrotechnic signalflares. A planting rack containing a mine simulator may be readilypicked up and moved with either a fork lift or an overhead crane. Duringassembly the following actions should be taken:

The instrument rack with components corresponding with the service minebeing simulated is installed. The arming delay and recovery timeperiods, each ranging between 1 and 999 hours, are preset in the timingmodule 142. The ship counter 148 is set for the desired number of countsper firing and the desired intership dead period. The event recorderdigital clock is adjusted to current real time.

Loading or removing the mine simulator from the planting rack isaccomplished by using the rack strongback with a suspension sling froman overhead crane. Lugs welded to the sides of the tail plate/shroudassembly provide lifting points for the assembled mine simulator andfloat. Holes in the mine fin plates provide lifting points for theunassembled mine case. A rope railing secured around the top of thefloat provides both the lifting points for handling the float andhoisting the float from the water during recovery operations.

During mine simulator assembly, the inert mine simulator is removed fromthe release rack and is placed on an assembly jig where the instrumentrack assembly and sensors corresponding to the simulated service mineare installed. The signal flares, squib actuators, and CO₂ cartridgesare installed in the float assembly. The crystal controlled oscillatorcircuit for the timing module and event recorder is energized, and theevent recorder is adjusted to current real time. Upon completion of mineassembly the mine simulator is placed in the release rack or plantingrack and secured awaiting pickup, delivery, and planting operation.

At the planting site the release rack with enclosed mine simulator isplaced in a cleared, open area and picked up by a hovering helicoptertrailing an 18 foot nylon pendant from its cargo hook. Ground handlingpersonnel engage the pendant swivel hook in the rack strongback liftingeye. After planting, the empty rack is returned to the cleared area,disengaged from the helicopter and stored, pending later recovery of themine simulator. When using helicopter delivery, care should be taken todischarge any static electrical charge accumulated on the helicopter,pendant, or rack for personnel safety. Helicopter mine simulatorreleasing limitations are 0 to 50 feet altitude and 0 to 15 knots groundspeed with optimum conditions at 30 feet altitude and 10 knots groundspeed. A second method of delivering the mine simulator is by surfacecraft where the rack with enclosed actuation mine simulator is picked upand suspended over the side from the ship cargo handling boom.

In both methods of delivery, the mine simulator electrical releaseactuator circuit is connected to a remote control box through a quickdisconnect fitting located near the pendant hook. The electricalconnection is made at the same time the pendant hook is engaged in therack lifting eye. The remote control box consists of a small, hand heldbox containing batteries, electrical switches, indicator lights, and anelectrical extension cord. The control box allows the operator to checkcontinuity of the mine releasing circuit and to electrically power thelinear actuator release mechanism. The extension cord from the controlbox to the rack releasing device has a quick disconnect fitting tofacilitate electrical hook up at the same time the rack is picked up forplanting operations.

Immediately after the rack and mine assembly has been picked up by thehelicopter or boom for transporting to the planting site, the controlbox is connected to the rack releasing mechanism and a continuity checkis made on all of the linear actuator circuits to insure thatconnections are intact before leaving the pickup area. Electricalcontinuity checks are again made at the planting site to verify thatconnectors have not become separated enroute.

Upon impact with the water, float buoyancy causes the float to separatefrom the mine case as the mine simulator submerges. However, the floatremains attached to the mine case by a short 3 foot tether line. Anunderwater electrical firing cable and recovery line also remainattached between the float and the mine case. Hydrostatic pressureswitch 161 energizes the timing module clock at an 18 foot depth tostart the delay arm and recovery time period. As the mine settles into ahorizontal position on the bottom surface, the float remains mooredapproximately 3 feet above it.

After completion of arming delay period and upon receipt of the propertype, sequence, and number of sensor looks, a signal is sent to theactuation counter 148, causing it to step down 1 number from its presentship count setting. This process is repeated, stepping down 1 additionalnumber each time until the actuation counter reaches 0 at which time afiring signal is passed to the float, allowing one signal flare to beejected. The actuation counter then automatically returns to its initialsetting. The signal flare is armed during ejection and ignited when itreaches the surface. The ignited flare produces a heavy colored smokefor a short period of time followed by a flame of the same color for anadditional short period of time.

Upon completion of the recovery time period set in the timing module142, a squib powered cable cutter or line cutter 152 is actuated tosever the float tether line 211. The float rises to the surface payingout a self-contained recovery line 212 attached to the submerged minecase 110A at the tail plate/shroud assembly 118. As the float rises, theunderwater electrical firing cable connector 111 is pulled free from itsreceptacle in the float bottom cover plate.

Mine simulator recovery is conducted by surface craft only. Tofacilitate visual acquistion of the surface float, it is painted brightorange and white. Under adverse lighting conditions, a flashing markerbeacon 261 is activated as the float reaches the surface. A back upsystem consisting of an acoustic pinger located in the submerged minecase 110A is also activated to aid in determining mine position if thefloat should fail to surface. The surfaced float, which weighsapproximatly 85 pounds with flares expended, is retrieved manually, andthe attached recovery line removed. The float is then lifted manually orhoisted aboard the recovery ship. The recovery line slack is removed bypulling on the recovery line until the recovery ship is directly overthe submerged mine. The recovery line is then used to hoist thesubmerged mine aboard the recovery ship or mine tender 10. The recoveredsimulator is then washed down with fresh water and replaced with itsfloat in an empty planting rack for protective storage and handling. Thepresent mine simulator may be made to simulate a wide variety of servicemines merely by including components from those mines withininstrumentation rack 117 so as to duplicate the interior mechanisms.

The foregoing description taken together with the appended claimsconstitute a disclosure such as to enable one skilled in the mine layingarts and having the benefit of the teachings containd therein to makeand use the invention. Further, the structure and methods describedtherein may be seen to constitute an advance in the art which isunobvious to an artisan not having the benefit of such teachings.

Obviously many modifications and variations of the present invention arepossible in light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced other than as specifically described.

What is claimed is:
 1. A mine simulator, comprising:a housing defining awater-tight compartment; a float having a plurality of signalingdevices; a tetherline having two ends and a first predetermined finitelength, said line being attached on one end to said housing and attachedon the other end to said float; detecting means within said compartmentfor producing a ship count signal in response to the proximate passageof a body; processing means within said compartment and communicatingwith said detecting means for producing a signaling device launch signalin response to a predetermined number of said ship count signals;recording means within said compartment and communicating with saidprocessing means for making a permanent record of said ship countsignals; and sequencing means within said float communicating with saidprocessing means and with said signaling devices for selectivelyactivating said signaling devices in response to said launch signals. 2.A mine simulator as set forth in claim 1, further comprising:a timerwithin said compartment having means for generating a terminationcommand in response to predetermined conditions; and an acoustictransmitter within said compartment, communicating with said timer, andconfigured to broadcast an acoustic signal in response to saidtermination command.
 3. A mine simulator as set forth in claim 1,further comprising:a timer within said compartment having means forgenerating a termination command at a preselected time; and line partingmeans attached to said housing and engaging said tetherline for cuttingsaid tetherline in response to said termination command.
 4. A minesimulator as set forth in claim 1, further comprising:an electricalswitch attached to said float, operative to control flow of electriccurrent, and responsive to light intensity in the float environment; andan electric beacon attached to said float and powered by electriccurrent controlled by said switch.
 5. A mine simulator as set forth inclaim 1, further comprising:a recovery line having two ends and a secondpredetermined finite length, said recovery line being attached on oneend to said float, and on the other end to said housing; said secondpredetermined finite length being greater than said first predeterminedfinite length.
 6. A mine simulator as set forth in claim 1 wherein saidfloat has a plurality of launching devices, one for each signalingdevice, each launching device comprising:said float defining a firstvolume configured to contain a signaling device, and having two ends anda cylindrical wall; a detachable cover sealingly attached to said floatand abutting one end of said first volume; an ejector piston havingfirst and second sides, sealingly engaging said cylindrical wall andslidable between first and second positions, said first side of saidejector piston abutting said other end of said first volume; a containerfor high pressure gas, having a frangible seal; high pressure gas withinsaid container; manifold means, including said second side of saidejector piston, for confining said high pressure gas and enclosing saidcontainer, and firing pin means communicating with said sequencing meansfor rupturing said frangible seal in response to selective activation ofa signaling device by said sequencing means.
 7. A mine simulator as setforth in claim 1, further comprising:pressure sensitive means connectedto said processing means for producing a ship count signal in responseto a change in ambient pressure.
 8. A mine simulator as set forth inclaim 1, further comprising:sound detection means connected to saidprocessing means for producing a ship count signal in response toacoustic energy.
 9. A mine simulator as set forth in claim 1 whereinsaid detecting means comprises a passive search coil.
 10. A minesimulator as set forth in claim 1 wherein said housing comprisesstainless steel.
 11. A mine simulator as set forth in claim 1, whereinsaid housing has a plurality of external fins.
 12. A mine simulator asset forth in claim 1, further comprising an apertured hemisphericalaluminum nose piece.
 13. A mine simulator as set forth in claim 1,further comprising a sacrifical metallic cathode electrically connectedto the exterior of said housing.
 14. A mine simulator as set forth inclaim 1, wherein said float encloses six separate signaling devices. 15.A mine simulator as set forth in claim 1, wherein said signaling devicesare buoyant smoke flares.
 16. A mine simulator as set forth in claim 1in combination with a planting rack.
 17. A mine simulator as set forthin claim 1, wherein said housing includes frictional means for payingout said tetherline in response to tension in said tetherline caused bybuoyant forces acting on said float.
 18. A mine simulator as set forthin claim 1, wherein said recording means comprises a digital recorderand a length of electrosensitive paper tape.
 19. A mine simulator as setforth in claim 1 wherein said recording means is configured to recordship count pulses by event number and time of occurence.
 20. A minesimulator as set forth in claim 1 wherein said sequencing meanscomprises a solid-state stepping device.
 21. A mine simulator as setforth in claim 2 wherein said timer generates a termination command inresponse to said housing compartment becoming flooded.
 22. A minesimulator as set forth in claim 2, wherein said timer generates atermination command at a preselected time after planting.
 23. A minesimulator as set forth in claim 3, wherein said line parting meanscomprises an electrically initiated squib powered guillotine linecutter.
 24. A mine simulator as set forth in claim 5 wherein said floathas drum means for accepting and releasably retaining said recovery linein a coiled configuration.
 25. A mine simulator as set forth in claim 6,wherein said float has six launching devices.
 26. A mine simulator asset forth in claim 6, wherein said high pressure gas comprises carbondioxide.
 27. A mine simulator as set forth in claim 6 wherein saidfiring pin means comprises an electrically initiated squib and a spikedpiston configured to be propelled by said squib.
 28. A mine simulator asset forth in claim 8 wherein said sound detection means comprises ahydrophone.
 29. A mine simulator, comprising:a stainless steel casedefining a housing open on one end and having a plurality of externalfins; a tailplate/shroud sealingly attached to said case open enddefining a water tight compartment within said case; a float having aplurality of separate signaling devices; a tetherline attached on oneend to said case, and attached on the other end to said float; arecovery line attached on one end to said case and attached on the otherend to said float; instrumentation means contained within saidcompartment and communicating with said float for activating saidsignaling devices, one at a time, in response to environmentaldisturbances; and an aluminum hemispherical nose piece attached to saidcase opposite said tailplate/shroud.
 30. A mine simulator as set forthin claim 29 wherein said aluminum hemispherical nose piece iselectrically connected to said stainless steel case and serves as asacrificial cathode.
 31. A mine simulator as set forth in claim 29,wherein said float has piston means for pneumatically expelling saidsignaling devices, one at a time.
 32. A mine simulator as set forth inclaim 29, wherein said signaling devices are buoyant smoke flares.
 33. Amine simulator as set forth in claim 29, in combination with a plantingrack.
 34. A mine simulator as set forth in claim 29, wherein saidinstrumentation means includes detecting means for sensing environmentaldisturbances, firing module means for generating a ship count signal inresponse to an environmental disturbance, counting means fortransmitting a signalling device launch signal in response to apredetermined number of ship count signals, recording means forrecording each ship count, and sequencing means for launching each ofsaid signaling devices, one at a time, in a predetermined order.
 35. Amine simulator as set forth in claim 34 wherein said instrumentationmeans further comprises a timer for activating said detecting meansduring a predetermined time period.
 36. A mine simulator as set forth inclaim 35 further comprising a hydrostatic switch attached to said minesimulator and operative to control flow of electric power to said timerin response to predetermined ambient pressure.